DSCompress

[OSW]

DScompress version 1.3 is out. see the source topic that this thread links on the front page.

well, some games can be compressed very well.
for example many i've tried compress result in about half the size (already trimmed roms by the way)

The best usage is to compress files you want to keep on your cart, but you don't use very often.
It's also probably not worth using with files which are greater than 40ish megabytes

IBNobody: Save game compression is pretty useless. you wouldn't save much space and it would be very annoying to have to enter a program just to decompress usch a small file.
for example my Saves on ez4 (not all 512kb like some carts) total up to 4 megabytes. thats about 9 NDS gamesaves and 16 GBA gamesaves.

 

[Glacius0]

Here's some math on how much space compressing may save you.

high assumption: 1 gb cart, 25% compression rate, 128 mb roms only
1024 / 128 = 8 (roms)
1024 / 4 (25%) = 256 mb
256 - 128 (extraction space) = 128 mb
Result: one extra rom (3 roms for a 2 gb cart or 64 mb roms, 7 for both)
Rom efficiency: 112% (119% roms for a 2 gb cart or 64 mb roms, 122% for both)

realistic assumption: average number of roms on 1 gb cart = 20
1024 / 20 = 51.2 mb (average rom size)
1024 / 4 (25%) = 256 mb
256 - 128 (extraction space) = 128 mb
result: 128 / 51.2 = 2.5 extra roms (7.5 roms for a 2 gb cart)
rom efficiency: 112.5% (119% for a 2 gb cart)

Conclusion: By average, you get 12% more roms on a 1 gb cart and 20% on a 2 gb.
You have to draw your own conclusion if that's worth the loading time.
Keep in mind the actual compression rate may be worse.

Opinion: for a 1 gb cart you're better off getting a 2gb microSD card. For a 2 gb cart, if the loading times are under 20 seconds for a 128mb rom it could be worth it to some. However, I expect loading times longer than that, and if not, then the compression rate will be worse, so to me I don't think it's worth it.

 

[OSW]

You overly complicated your math!

some roms can be compressed much more than others (even pretrimmed)

Pokemon diamond Trimmed: 58.3 megabytes
Trimmed then Compressed with 7zip: 26.1 megabytes
saving of 32 megabytes or 65.2%

Donkey Kong - King of Swing: 16 megabytes
Compressed with 7zip: 3 megabytes
saving of 13 megabytes or 81% LOLOLOLOLOLOLOLOLOLOLOLOL

The ones which compress alot are the best top use with this app.
Simply don't use this program on files which don't compress much.

 

[IBNobody]

Ok, apparently I'm not allowed to have an opinion anymore. Let me explain WHY THIS HAS NO USEFUL PURPOSE AS A STAND-ALONE APP. Let's say you have a 1GB MicroSD card and a 32MB ROM. You use this to compress the rom to 28MB. You need 32MB of extra space to extract it into. So, when trying to play any game, the size it takes is Orignal Size + Compressed Size. In this case, it takes 60MB for a 32MB rom. And to make it worse, what if you have a lot of small, 8 or 16MB roms and one 128MB rom. You need empty space equal the uncompressed size of the largest rom.

HOWEVER, this would be useful for small files like saves IF it were built into the flash cart. It could uncompress them only when it needed to, like when saving.

You're only considering one ROM at a time. Zipping usually yields a compression rate of 50%-75% of the file size. Assume you have an average compression rate of 75%. Leaving a scratch 100MB on a 1GB card (for restores) would give you 900MB. That space could hold 1.125GB of ROMs. (I'm simplifying the numbers a little here.) You're limited to playing one game at a time, but you'll have extra storage, above and beyond what you'd normally have.

Whether or not this is a good thing depends on your flashcart. If you use something with removable storage, compression is of less use to you. You can just swap out the micro SD card. If you bought a G6 Real or a DS-X, though, compression is the only way you can increase the size of your card.

 

[IBNobody]

IBNobody: Save game compression is pretty useless. you wouldn't save much space and it would be very annoying to have to enter a program just to decompress usch a small file.
for example my Saves on ez4 (not all 512kb like some carts) total up to 4 megabytes. thats about 9 NDS gamesaves and 16 GBA gamesaves.

I won't argue against having it integrated into the cart OS. That is the best way to go. The guy's providing his source; maybe other flash teams will pick it up?

Saves on my R4 right now total 12MB. On my DS-X, they'd be less than 200KB. Actually, my 30-save archive is 67k compressed and 16MB uncompressed.

 

[Glacius0]

You overly complicated your math!

some roms can be compressed much more than others (even pretrimmed)

Pokemon diamond Trimmed: 58.3 megabytes
Trimmed then Compressed with 7zip: 26.1 megabytes
saving of 32 megabytes or 65.2%

Donkey Kong - King of Swing: 16 megabytes
Compressed with 7zip: 3 megabytes
saving of 13 megabytes or 81% LOLOLOLOLOLOLOLOLOLOLOLOL

The ones which compress alot are the best top use with this app.
Simply don't use this program on files which don't compress much.

You still need a 128 mb buffer to unpack it to. Only compressing a few roms makes no sense. My point is that you can't say because some roms compress 50% you can have 50% more roms on your cart.

 

[kellyan95]

Ok, apparently I'm not allowed to have an opinion anymore. Let me explain WHY THIS HAS NO USEFUL PURPOSE AS A STAND-ALONE APP. Let's say you have a 1GB MicroSD card and a 32MB ROM. You use this to compress the rom to 28MB. You need 32MB of extra space to extract it into. So, when trying to play any game, the size it takes is Orignal Size + Compressed Size. In this case, it takes 60MB for a 32MB rom. And to make it worse, what if you have a lot of small, 8 or 16MB roms and one 128MB rom. You need empty space equal the uncompressed size of the largest rom.

HOWEVER, this would be useful for small files like saves IF it were built into the flash cart. It could uncompress them only when it needed to, like when saving.


You're only considering one ROM at a time. Zipping usually yields a compression rate of 50%-75% of the file size. Assume you have an average compression rate of 75%. Leaving a scratch 100MB on a 1GB card (for restores) would give you 900MB. That space could hold 1.125GB of ROMs. (I'm simplifying the numbers a little here.) You're limited to playing one game at a time, but you'll have extra storage, above and beyond what you'd normally have.

Whether or not this is a good thing depends on your flashcart. If you use something with removable storage, compression is of less use to you. You can just swap out the micro SD card. If you bought a G6 Real or a DS-X, though, compression is the only way you can increase the size of your card.

Ok, let's have somebody get 12 random games (at least 1 of every size) and compress them all with THIS utility. See how long it takes, and how much actual space is saved

 

[OSW]

Yeah well my point is that you shouldn't bother compressing files that won't compress very much.

Another obvious suggestion, don't compress files you regularly use (since you don't have to wait decompressing times)

Common sense if you ask me.

So if you compress Two 50mbyte files that can be compressed to 50% size, then you don't need more room than you originally had on your cart to uncompress it.

Compress more files and you start saving more.


I understand some slot carts offer compression features. I think it'd be useful if we had a general app which could uncompress to the ram of other carts which don't have the feature built in.

 

[kellyan95]

I doubt most people would be able to do the math needed for efficient use of this program.

 

[Glacius0]

Yeah well my point is that you shouldn't bother compressing files that won't compress very much.

Another obvious suggestion, don't compress files you regularly use (since you don't have to wait decompressing times)

Common sense if you ask me.

So if you compress Two 50mbyte files that can be compressed to 50% size, then you don't need more room than you originally had on your cart to uncompress it.

Compress more files and you start saving more.


I understand some slot carts offer compression features. I think it'd be useful if we had a general app which could uncompress to the ram of other carts which don't have the feature built in.

Again, you are forgetting you need a place to unpack the rom. If you have two 50 mb files, compressed to 25 mb, you need 50 mb of free space to unpack it to. Meaning you saved 0 mb.

 

[OSW]

No i didn't forget that

I meant exactly that that when you unpack it there is the right amount of room.
now if you increased the number of compressed files then the room increases and you do indeed save space.

Besides, despite how i may have sounded, i don't mean to force anyone to accept my opinion on the merits of the app, i just wish to explain how i find it to be best used and how i personally find it useful.

I'm not compressing a huge amount of files on my cart at the moment.
I have
5 compressed gba games (and 12 uncompressed, 4 in NOR)
1 compressed nds game (9 uncompressed)
1 compressed kernel update

now here is the biggest part
50 compressed homebrew games/demos (36.8mb)(uncompressed is 76.8mb)

with the 40mb saved i can fit a dpg video in, since on average the homebrew is 1.5mb.

these are average or good homebrew which i might use once every 2 months or so.

 

[Kamgusta]

can be useful if you want to have all your roms gzipped on your cart...
then you can decompress the roms you want to play (and delete others to save space)
So it is useless. Trim anyone?

If you think it is useless since trimming exists, sorry but you just don't know what both do...

Let's take a simple example here, with a fictive rom that simply contains 56 characters (hope big-N won't sue me for posting its "code" !

).

64 bytes rom (512 bits

) :
ABCDABCDABCDABCDABCDABCDABCDABCDABCDABCDABCDABCDABCDABCD00000000

The zeroes are there because of the storage format; as the size of the cartridge will be the nearest higher power of 2, the remaining space is occupied by zeroes, which don't do anything in that case.

Now let's trim it :
ABCDABCDABCDABCDABCDABCDABCDABCDABCDABCDABCDABCDABCDABCD
A 56 bytes rom.

We have saved some room!

But now, let's try compressing it instead...

(ABCD)*14(0)*8
A 14 bytes rom!

Weee, it is now even smaller! Trimming just trims what isn't need (oddly reminds another topic from here!) , whereas compressing makes what exists take much less space, without losing anything in this case.

I hope you understand the difference better now, and realize the use this could have!

- Vince989

I didn't say trim=compress

0556 Megaman ZX (U)
67.108.864 byte

TRIM
45.798.068 byte

ZIP
34.743.252 byte

Let's do some math. The time you wast zipping could be used to earn 5$ and buy 512MB more storage... if that is the problem.

 

[A2hok]

This program COULD be usefull only if the speed of unzipping was optimized. At the moment it takes over a minute to unzip generally. This is just way too much, if the time could be less this would be a very good program.

In other words, its just way too slow.

 

[Maikel Steneker]

This could be useful in another way. I've got both a M3 Simply and M3 Lite. Wouldn't it be possible to compress a GBA-rom and directly uncompress it to the M3 Lite memory? It would mean that you don't need any space to uncompress your roms to.

This program could also be useful in another way: like going on vacation. You could compress all of your roms, and use the space you're saving to put some DPG-files on your flashcart. You can watch the movies, and after you saw them you delete them (using DSOrganize or something) leaving space to unpack your roms!

 

[Njosnavelin]

it would be better if the roms could be automatically unzipped when wanting to play and ziped again when stop playing


Yeah, because waiting for a full minute before you can play a portable game makes so much sense!

PSP fanboys would happen to agree.

 

[Groundhog]

Beware, DsCompress 1.3 is bugged. I don't know for the older versions since this is the first one I use.

I made several tests with a 16Mb (bytes, not bits) file on my M3 micro-SD. Here are the results :

- Winzip compression, maximum portable .zip, uncompressed with DsCompress, resulting file corrupted.
- Original Gzip (command line), default options, uncompressed with DsCompress, resulting file corrupted.
- 7Zip, Gzip Ultra mode, uncompressed with DsCompress, resulting file >>> OK > CORRECT